Beam measuring equipment and beam measuring method using the same

ABSTRACT

A measuring device includes a magnetic shielding part for shielding an outer magnetic field, and a plurality of magnetic field sensors which are arranged in a shielding space which is formed by the magnetic shielding part, wherein the magnetic field sensor includes a plurality of magnetic field collection mechanisms which collect magnetic fields which the beam current to be measured generates, and the magnetic field collection mechanism is a cylindrical structural body which has at least a surface thereof formed of a superconductive body and includes a bridge portion which has only a portion thereof formed of a superconductive body on an outer peripheral portion thereof, and a magnetic field which the beam current to be measured generates is measured by the magnetic field sensors. Due to the arrangement of the plurality of magnetic field sensors, a beam position and a beam current can be detected.

TECHNICAL FIELD

The present invention relates to a beam measuring device and a beammeasuring method which uses the beam measuring device, and moreparticularly to a device which measures a beam current value and aposition without interrupting ion beams.

BACKGROUND OF THE INVENTION

As a method for measuring a current value of ion beams withoutinterrupting the beams with high accuracy, several studies have beenreported conventionally (see non-patent document 1). This methodmeasures a beam current value by detecting a magnetic field which a beamcurrent generates using a sensor which is referred to as SQUID whichuses a Josephson coupling method which is an extremely sensitivemagnetic field sensor. The SQUID includes one (RF-SQUID) or two(DC-SQUID) Josephson junctions in a super-conductive ring, and measuresa magnetic flux which penetrates the super-conductive ring using amagnetic flux quantum (2.07×10⁻¹⁵ Wb) as a scale.

In the above-mentioned document, the SQUID which uses a low-temperaturesuperconductive body which is operated at a temperature of liquefiedhelium is used. Further, the beam current measuring device has a mainpart thereof constituted of a detecting part which detects a magneticfield corresponding to a beam current, a magnetic flux transmitting partwhich transmits a magnetic flux to a measuring part, the measuring partwhich includes a superconductive element which responses to thetransmitted magnetic flux and a feedback coil which allows a feedbackcurrent such that the feedback current cancels a change of the magneticflux which penetrates the superconductive element, and a magneticshielding part made of a superconductive body and having a gap whichmagnetically shields the detecting part, the magnetic flux measuringpart and the measuring part from an outer space which includes a spacein which ion beams flow.

The detecting part is a coil which is formed by winding a superconductive line on a core made of a soft magnetic core and induces asuperconductive current into the coil by collecting magnetic fieldswhich are generated by the beam current by the soft magnetic core. Then,this superconductive current induced in the coil is transmitted to thecoil which is arranged close to the SQUID. That is, in response to thechange of the beam current, the superconductive current which flows inthe coil is changed thus changing a quantity of magnetic flux whichflows in the SQUID. The feedback coil is provided for allowing thefeedback current to flow so as to cancel the change of the magneticflux. The feedback current is proportional to the change of the beamcurrent value and the change quantity of the beam current value can bedetermined by measuring the feedback current.

Recently, a measuring method of the beam current value using ahigh-temperature superconductive body has been studied (see non-patentdocument 2). According to the method described in this non-patentdocument 2, a cylinder which has a surface thereof coated with ahigh-temperature superconductive body constitutes a detecting part.However, on an outer peripheral surface of the cylinder, a bridgeportion which has a portion thereof made of a high-temperaturesuperconductive body is formed. A beam current which penetrates thecenter of the cylinder induces a surface shielding current on a surfaceof the cylinder. Here, the surface shielding current concentrates on thebridge portion. Then, a magnetic flux which is generated by theconcentrated surface shielding current is measured by a SQUID. The SQUIDwhich is used in this method uses the high-temperature superconductivebody and is operable at a liquefied nitrogen temperature or more.

The beam current measuring device which uses the former SQUID made ofthe low-temperature superconductive body can measure the beam currentwith a noise band corresponding to several nA.

On the other hand, the beam current measuring device which uses thelatter SQUID made of the high-temperature superconductive body has anadvantage that the measuring device can be operated with only liquefiednitrogen or a freezer, a noise band is considered to be large, that is,around several μA (see non-patent literature 2). Further, a drift on azero point is considered to be large and there has been a drawback that,in an actual measurement for several tens seconds or more, the measuringdevice can only measure the beam current substantially corresponding to10 μA or more. To the contrary, there has been a report that bydesigning the magnetic shielding such that the sensitivity of thehigh-temperature superconductive SQUID is optimized, ion beams of 1.8 μAare successfully measured (see patent document 1, patent document 2,non-patent document 3). Here, the noise band corresponding to 0.5 μA. Inthis manner, recently, the studies and developments of thehigh-temperature superconductive SQUID have been in progress.

In other non-destructive measuring method, a DC current transformer isused. The noise band is approximately 0.5 μA to several μA although thenoise band depends on the design of the magnetic shielding.

Non patent literature 1: Superconducting Quantum Interference Devicesand Their Applications (Walter de Gruyter, 1977) p. 311,IEEETRANSACTIONS ON MAGNETICS, VOL. MAG-21, NO. 2, MARCH 1985,Proc, 5^(th)European Particle Accelerator Conf., Sitges, 1996 (Institute of Physics,1997) p. 1627, Publication of Japan society of physics Vol. 54, No. 1,1999Non patent literature 2: IEEE TRANSACTION ON APPLIED SUPERCONDUCTIVITY,VOL. 11, NO. 1, MARCH 2001 p. 635Non patent literature 3: CNS annual reportPatent literature 1: Japanese Patent Application 2003-155407Patent literature 2: Japanese Patent Application 2003-331848

DISCLOSURE OF INVENTION Problems to be Solves by the Invention

Although various non-destructive measuring methods have been proposed,the sensitivity to the beam current is high and hence, these measuringmethods cannot measure the current value and the position of the beamssimultaneously.

Accordingly, in a beam line of an accelerator or an ion implantingapparatus, for example, a Faraday cup and a beam profile monitor arerespectively arranged. Further, currently, results which are obtained byrespective measurements are combined and the current value and theposition of the beams are grasped based on the combined results.

Under such circumstances, there has been a demand for a beam measuringdevice which can measure beams in a non-destructive manner can measure abeam current value with high accuracy, and can also grasp positions ofthe beam.

The present invention has been made under such circumstances and it isan object of the present invention to provide a beam measuring devicewhich can realize the non-destructive measurement of a beam currentvalue with high accuracy and also can measure positions of the beams.

Means for Solving the Problem

To achieve the above-mentioned object, according to the presentinvention, a measuring device includes a magnetic shielding part forshielding an outer magnetic field, and a plurality of magnetic fieldsensors which are arranged in a shielding space which is formed by themagnetic shielding part, wherein the magnetic field sensor includes aplurality of magnetic field collection mechanisms which collect magneticfields which the beam current to be measured generates, and the magneticfield collection mechanism concentrates a superconductive surfaceshielding current which the beam current generates in the vicinity ofthe respective magnetic field sensors.

Inventors of the present invention, based on results of variousexperiments carried out using high-temperature superconductive bodiesand studies on the principle of a mechanism which collects magneticfields generated by a beam current to be measured, have found out thatwith the provision of a plurality of mechanisms which collect themagnetic fields, it is possible to measure not only a beam current valuebut also positions of the beams. The present invention has been made byfocusing on this point.

Further, in the beam measuring device of the present invention, themagnetic field collection mechanisms are arranged such that the beamcurrent is concentrated on a predetermined region since asuperconductive surface shielding current is interrupted within a rangeof a fixed length in a plane which the beam current penetrates exceptfor a predetermined region. Due to such a method, it is possible toefficiently take out the surface shielding current.

Further, the beam measuring device of the present invention includes themagnetic field collection mechanism which is a cylindrical structuralbody having at least a surface thereof formed of a superconductive bodyand having a bridge portion which has only a portion thereof constitutedof a high-temperature superconductive body on an outer peripheralportion.

According to this method, it is possible to efficiently concentrate theshielding current in a state that the magnetic field collectionmechanism possesses the extremely small resistance.

Further, the beam measuring device of the present invention includesmagnetic field collection mechanism which is constituted of a pluralityof superconductive coils.

Due to such a constitution, it is possible to increase the degree offreedom with respect to the magnetic field sensor arrangement position.

Here, it is preferable to arrange the magnetic field collectionmechanism in the vicinity of the magnetic field sensor. However, whenthe superconductive coil is used as the magnetic field collectionmechanism, the superconductive coil maybe arranged in a spaced-apartmanner from the magnetic field sensor. That is, the superconductive coilmaybe arranged close to the beam current and the magnetic field sensormay be arranged in a spatial range which is highly magnetically sealedand has small noises. Then, a superconductive circuit which transmitsthe magnetic field which the beam current collected by thesuperconductive coil generates to the magnetic field sensor may beintroduced. Although the superconductive circuit, currently, can beformed only with the low-temperature superconductive body which has thehigh degree of freedom of shape, when the superconductive coil is used,it is possible to introduce the superconductive circuit which cantransmit the magnetic field simultaneously and hence, it is possible toform the superconductive coil without arranging the superconductive coilin the vicinity of the beam current.

Further, the beam measuring device of the present invention includes thesuperconductive coil which is wound around a core which is constitutedof a soft magnetic body.

Due to such a constitution, it is possible to obtain the highersensitivity.

According to the present invention, by constituting the beam measuringdevice using a plurality of magnetic field sensors and by calculatingsignals which are measured by the respective magnetic field sensors, itis possible to measure not only the beam current value but also theposition of the beams.

Due to such a constitution, it is possible to provide the beam measuringdevice which can measure the beams in the non-destructive measurementwith a noise width less than approximately 0.5 μA, and can measure theposition of the beam simultaneously.

Further, according to the present invention, by performing thecalculation such that noise signals having the same phase as outputsignals of the plurality of magnetic field sensors can be cancelled fromsuch output signals, the noise width can be made further smaller thusenabling the measurement with high accuracy.

Further, the magnetic field sensor may preferably be a SQUID.

Here, the use of the high-temperature superconductive body is preferablesince the beam measuring device is operable at a liquid nitrogentemperature or more. With the use of the high-temperaturesuperconductive body, a running cost can be reduced and, at the sametime, a thickness of a shielding portion can be reduced thus realizingthe miniaturization of the beam measuring device.

For example, by applying the beam measuring device to an ionimplantation device which is required to measure the beam current ofseveral μA to several tens mA with high accuracy, it is possible tomeasure the current value and the positions of the beams in anon-destructive manner simultaneously by radiating ion beams to asemiconductor wafer.

Further, the beam current and position measuring method of the presentinvention uses the above-mentioned beam measuring device, arranges thebeam measuring device on the beam line which is radiated to a materialto be treated from an ion source or an electron beam source, andmeasures the beam current value of the beam line and the position of ionbeams based on outputs of the magnetic field sensors.

It is desirable to simultaneously measure the beam current value of thebeam line and the position of the ion beams since such simultaneousmeasurement enables the efficient control and adjustment of beams.

Further, the beam control method of the present invention includes ameasurement step which measures a beam current of beams which aregenerated using an ion source or an electron beam source using theabove-mentioned beam current and position measuring method, and acontrol step which feedbacks the beam current value and positions ofbeams which are obtained by the measuring step or both of the beamcurrent value and the positions of beams to control parameters of theion source, the electron beam source, an analysis electric magnet, apart for applying an electric field and a magnetic field to the beams.

Further, a beam radiation method of the present invention ischaracterized by including a radiation step which radiates the beamcurrent which is controlled using the control parameters obtained by thebeam control and adjustment step to a material to be treated withrespect to the beams generated using the ion source or the electron beamsource.

Further, according to the beam irradiation device which uses theabove-mentioned beam measuring device, it is possible to perform thebeam radiation while controlling the beam current value and the positionwith high accuracy and hence, the working of high accuracy can berealized. Further, the adjustment of the beams is facilitated.

Further, the present invention is also effectively applicable to anactive element such as a semiconductor, liquid crystal, a bio chip, apassive element such as resistance, coil, a capacitor or the like, anelectric line or the like which is manufactured or inspected using anion injection device, an electronic beam exposure device, an acceleratoror an electron beam vapor deposition device which includes theabove-mentioned beam measuring device.

Advantage of the Invention

According to the present invention, with the use of the plurality ofmagnetic field sensors, it is possible to measure not only a beamcurrent but also a position of beams easily and in a non-contact manner.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing a circuit diagram of a high temperaturesuperconducting SQUID and a flux-locked loop used in a beam measurementdevice of a first embodiment of the present invention.

FIG. 2 is a view showing a schematic appearance of a magnetic fieldsensor of the first embodiment of the present invention.

FIG. 3 is a view for explaining the relationship between the magneticfield sensor and beam positions of the first embodiment of the presentinvention.

FIG. 4 is a view showing a schematic appearance of a magnetic fieldsensor of a second embodiment of the present invention.

FIG. 5 is a view for explaining the relationship between the magneticfield sensor and beam positions of the second embodiment of the presentinvention.

FIG. 6 is a view showing a schematic appearance of a magnetic fieldsensor of a third embodiment of the present invention.

FIG. 7 is a view showing a schematic appearance of the magnetic fieldsensor of the third embodiment of the present invention.

FIG. 8 is a view showing a schematic appearance of a magnetic fieldsensor of a fourth embodiment of the present invention.

FIG. 9 is a view showing a schematic appearance of the magnetic fieldsensor of the fourth embodiment of the present invention.

FIG. 10 is a view for explaining the relationship between a magneticfield sensor and beam positions of a fifth embodiment of the presentinvention.

FIG. 11 is a view showing a schematic appearance of the magnetic fieldsensor of the fifth embodiment of the present invention.

FIG. 12 is a view for explaining the relationship between a magneticfield sensor and beam positions of a sixth embodiment of the presentinvention.

FIG. 13 is a view for explaining the relationship between the magneticfield sensor and beam positions of the sixth embodiment of the presentinvention.

FIG. 14 is a view for explaining the relationship between a magneticfield sensor and beam positions of a seventh embodiment of the presentinvention.

FIG. 15 is a view showing a schematic appearance of the magnetic fieldsensor of a comparison example.

In the drawing:

11: detection coil, 12: SQUID, 13: feedback coil, 15: SQUID input coil,100: mechanism which collects magnetic field, 100 a; base body which isformed of insulator or a normal conductive body, 100 b: high-temperaturesuperconductive body, 101: bridge part, S: slit

BEST MODE FOR CARRYING OUT THE INVENTION

Next, embodiments of the present invention are explained in detail inconjunction with the drawings.

First Embodiment

FIG. 1 is an explanatory view showing a circuit diagram of ahigh-temperature superconductive SQUID and a flux-locked loop used in abeam measuring device of the embodiment of the present invention.

The beam measuring device includes a magnetic shielding part forshielding an external magnetic field and a plurality of magnetic fieldsensors which are arranged in a shielded space formed by the magneticshielding part, wherein the beam measuring device is characterized inthat the magnetic field which a beam current to be measured generates ismeasured by the magnetic field sensor. The beam measurement device, asshown in FIG. 1, includes a detection coil 11 which is arranged in apath of a beam to be measured, a SQUID 12 which constitutes a magneticfield sensor which detects the magnetic field corresponding to the beamcurrent, a magnetic flux transmitting part which is constituted of thedetection coil 11 and a closed circuit of a SQUID input coil 15 andtransmits the magnetic flux detected by the detection coil 11 to ameasuring part, and a feedback coil 13 which allows a feedback currentto flow so as to cancel a change of the magnetic flux which penetratesthe SQUID, wherein the beam measurement device is configured such thatan output of the SQUID 12 is supplied to an output terminal through apreamplifier and an integrator and, at the same time, the output of theSQUID 12 is fed back to the feedback coil 13. Here, in order to erasenoises intrinsic to low frequencies of a Josephson element, an ACcurrent is biased to the beam measuring device.

A surrounded portion shown in FIG. 1 indicates a low temperature portionwhich is formed of the detection coil 11, the magnetic flux transmittingpart and the feedback coil 13 and the low temperature portion is fixedto a holder having a diameter of approximately φ4 cm and a height ofapproximately 2 cm. With respect to the holder in FIG. 2 to FIG. 8, forthe sake of convenience, a part of the low temperature portion which isincluded in the holder is shown as the SQUID in a representing manner.In addition, when a plurality of SQUIDs is depicted in the drawing, eachSQUID is identified as a SQUID_A, a SQUID_B and the like with suffixes.

The SQUID is, as shown in FIG. 2, arranged in the vicinity of amechanism which collects a magnetic field generated by the beam currentto be measured. The mechanism 100 which collects the magnetic field isformed of a cylindrical structural body which has a surface thereofcoated with a high-temperature superconductive body 100 b and has abridge portion 101 which has only a portion thereof constituted of ahigh-temperature superconductive body on an outer peripheral portion.When the beam penetrates a closed curved surface defined by an innerdiameter of the cylindrical structural body, a surface shielding currentis induced on an inner wall surface of the cylindrical structural bodyby the magnetic field generated by the beams. The surface shieldingcurrent flows in the direction opposite to the advancing direction ofthe beams on the inner wall surface of the cylindrical structural body.On the other hand, the surface shielding current flows in the same orforward direction as the advancing direction of the beam on the outerwall surface so that the surface shielding current makes a turn. Here,since the outer wall surface of the cylindrical structural body includesthe bridge portion 101 which is superconductive under high temperatureonly at a portion thereof and forms a slit portion S having nohigh-temperature superconductive body 100 b, the current does not flowinto the portion where a base body 100 a which is either an insulator ora normal conductor is exposed, thus the surface breaking currentconcentrates on the bridge portion. In this manner, the magnetic fieldgenerated by the beam current to be measured is collected. Further, themagnetic field which the concentrated surface shielding currentgenerates at the bridge portion is detected using the detection coil andis measured by the SQUID.

FIG. 3( b) is a cross-sectional view of the cylindrical structural bodyof FIG. 1 as viewed in the advancing direction of the beams in order toexplain the constitutional features of the present invention, and FIG.3( a) is a drawing of the cylindrical structural body as viewed in thedirection perpendicular to the advancing direction of the beam. As shownin FIG. 3( b), a cross-section of the cylindrical structural bodyobtained by cutting in the direction perpendicular to the advancingdirection of the beams is a rectangular shape. On two short sides of therectangular shape, SQUIDs are respectively arranged. FIG. 3( c) and FIG.3( d) are drawings showing an essential part of the configuration of thecylindrical structural body.

A beam_B5 is a beam which passes through the center of the rectangularshape. Outputs of the SQUID_A2 and the SQUID_B3 with respect to thebeam_B5 are equal.

Hereinafter, the measuring principle is explained in detail. Due to amagnetic field generated by the beam, on respective portions of an innerwall surface of the cylindrical structural body, a surface shieldingcurrent having a current value which differs depending on a magnitude ofthe magnetic field generated by the beam is induced. That is, assuming adistance from the center of the beam as R, the magnetic field which thebeam generates is attenuated in proportion to 1/R. Accordingly, whilethe surface shielding current having a large current value per unit areais induced in the portion of the inner wall of the cylindricalstructural body which is close to the beam center, the surface shieldingcurrent having a small value per unit area is induced in the portion ofthe inner wall which is apart from the beam center. Here, thedistribution of the surface shielding current which the beam_B5 induceson the inner wall is symmetrical with respect to an YZ plane. Thesurface shielding current which is induced on the inner wall flows inthe same or forward direction as the advancing direction of the beam onthe inner wall surface and, thereafter, turns around to an outer wallsurface and flows on the outer wall surface in the same or forwarddirection as the advancing direction of the beam. On the outer wallsurface of the cylindrical structural body, there exist two paths suchas a bridge_A1 and a bridge_B6, wherein the two paths are symmetricalwith respect to the YZ plane and a half of the total surface shieldingcurrent which is induced on the inner wall flows to the bridge_A1 andthe bridge_B6 respectively. In this manner, the outputs of the SQUID_A2and the SQUID_B3 are equal.

On the other hand, as indicated by the beam_A4, when the beam passes aposition in the minus direction along the X axis using the center of therectangular as an origin, the outputs of the SQUID_A2 and the SQUID_B3are not equal. In this case, the distribution of the surface shieldingcurrent which the beam_A4 induces on the inner wall is asymmetrical withrespect to the YZ plane. That is, on the inner wall at the minus side ofthe X axis, the surface shielding current having a large current valuecompared to the plus side is distributed and flows. Further, after thesurface shielding current flows on the inner wall surface in the same orforward direction as the advancing direction of the beam, the surfaceshielding current turns around to the outer wall surface whilemaintaining the substantially equal distribution. Then, the surfaceshielding current which flows along the outer wall at the minus side ofthe X axis flows toward a bridge_A1, while the surface shielding currentwhich flows along the outer wall at the plus side of the X axis flowstoward a bridge_B6 respectively. Accordingly, the output of the SQUID_A2is large compared to the output of the SQUID_B3. Further, the larger adistance between the position of the beam displaced in the minusdirection of the X axis and an origin, the output of SQUID_A2 becomeslarger than the output of the SQUID_B3.

By making use of this phenomenon, it is possible to measure the positionof the beam on the X axis. That is, assuming outputs of the SQUID_A2 andthe SQUID_B3 as V_(A)(X), V_(B)(X) respectively, a length of a long axisof the cylindrical structural body shown in FIG. 3( b) as D, and aposition sensitivity ratio as α, the position of the beam X iscalculated by a formulaX=(D/2)×α×(V_(A)(X)−V_(B)(X))/(V_(A)(X)−V_(B)(X)). Further, even whenthe beam is displaced from the X axis, since the structure of thecylindrical structural body is symmetrical with respect to the XZ planeshown in FIG. 3( b), it is apparent that an X coordinate of the positionwhich the beam passes through can be measured based on the sameprinciple.

The total sum of the surface shielding current induced on the inner wallsurface by the beam current which penetrates the closed curved surfaceformed by the inner diameter of the cylindrical structural body is fixedirrespective of the position of the beam. By making use of thisphenomenon, it is possible to calculate a beam current value bycalculating a sum of outputs of the SQUID_A2 and the SQUID_B3. That is,performing the calculation using the outputs of the SQUID_A2 and theSQUID_B3, the position on the X axis where the beam passes and the beamcurrent value can be measured simultaneously.

In the structure which arranges two SQUIDs, the position of the beam canbe measured single-dimensionally.

Second Embodiment

FIG. 4, FIG. 5( a) and FIG. 5( b) show an example of the constitutionwhich is modified to enable the two-dimensional measurement of theposition of the beam by expanding the principle. FIG. 5( b) is across-sectional view of the cylindrical structural body shown in FIG. 4as viewed in the beam advancing direction. Further, FIG. 5( a) is across-sectional view of the cylindrical structural body as viewed in thedirection perpendicular to the beam advancing direction. In thisconstitution, three bridges and three SQUIDs are respectively arranged.That is, in addition to the cases shown in FIG. 2, FIG. 3( a) and FIG.3( b) explained in conjunction with the embodiment 1, a bridge_C8 and aSQUID_7 are added on the Y axis. When the beam passes on the plus sideon the Y axis, compared to the case in which the beam passes on theminus side, the output of the SQUID_C7 becomes large, while the outputsof SQUID_A2 and the SQUID_B3 become small. In this manner, a ratio amongthree SQUIDs varies respectively depending on the position of the beam.In addition, coordinates of the beam position on the XY plane and theratio among outputs of three SQUIDS correspond to each other inone-to-one correspondence. That is, by calculating the ratio among theoutputs of three SQUIDs, it becomes possible to measure the beamposition two-dimensionally as the coordinate on the XY plane within therectangular cross section which is obtained by cutting the cylindricalstructural body perpendicular to the advancing direction of the beam.Here, by arranging two SQUIDs on the X axis direction and the Y axisdirection respectively, the beam position can be measuredtwo-dimensionally more easily.

Third Embodiment

FIG. 6 shows the structure which adopts one bridge and one SQUID and, inaddition, two magnetic field sensors. In this embodiment, thecylindrical structural body is constituted of a cylinder. That is, whilethe embodiment uses three sensors including the SQUID, the embodimentuses one bridge which constitutes a mechanism to collect the magneticfield. Here, as the magnetic field sensor, other sensor may be used inplace of the SQUID. Due to such a constitution, it is possible tomeasure the beam current value using the SQUID, and it is possible tomeasure the beam position separately using the magnetic field sensor_A10and the magnetic field sensor_B11.

Fourth Embodiment

FIG. 7 shows the structure which is basically same as the structure ofthe first embodiment shown in FIG. 2 and FIG. 3. However, thisembodiment adopts two bridges and two SQUIDs respectively. It isappreciated that by calculating outputs of the SQUID_A2 and theSQUID_B3, it is possible to measure the beam position one-dimensionallywith respect to a line which connects a SQUID_A2 and a SQUID_B3 and abeam current value simultaneously.

FIG. 8 and FIG. 9 show the structure in which an insulator or a normalconductor is designed such that surface shielding currents which arerespectively induced at positive and negative sides of an X axis on aninner wall of a cylindrical structural body are allowed to easily flowtoward bridges which are closer to these surface shielding currentsrespectively. By arranging the insulator or the normal conductor at thecenter portion of the outer wall of the cylindrical structural body in astate that the insulator or the conductor partitions the bridge_A1 andthe bridge_B6, the respective SQUID outputs can easily reflect the beampositions. In this embodiment, in a state that a whole surface of a basebody 100 a is covered with a superconductive body (100 b) , by forming aslit S in which the superconductive body is not applied and a base body(100 a) is exposed, a bridge_A1 and a bridge_B6 are separated from eachother. Here, the insulator or the usual-state superconductive body whichseparates the bridge_A1 and the bridge_B6 from each other may be alsoarranged effectively as shown in FIG. 10, FIG. 11, FIG. 12 and FIG. 13.

Fifth Embodiment

This embodiment shown in FIG. 10, FIG. 11( a) and FIG. 11( b) differsfrom the above-mentioned embodiments with respect to a point that a slitS which is formed in a portion of an outer wall of a cylindricalstructural body in the beam direction and is also formed to expose abase body from a superconductive body is formed to penetrate thesuperconductive body to reach edge faces of the cylindrical structuralbody. This embodiment is substantially equal to the above-mentionedembodiments with respect to other constitutions.

This embodiment is provided to optimize a shape of the slit S inconformity with a shape of the cylindrical structural body to increasethe above-mentioned position sensitivity coefficient as large aspossible.

Sixth Embodiment

This embodiment shown in FIG. 12, FIG. 13( a) and FIG. 13( b) differsfrom the above-mentioned fifth embodiment with respect to a point that aslit S which is formed to expose a base body from a superconductive bodyis formed to penetrate edge faces of the cylindrical structural body.This embodiment is substantially equal to the above-mentionedembodiments with respect to other constitutions.

By dividing a superconductive region along the direction of the beam inthis manner, the beam position is more clearly reflected thus enhancingthe detection accuracy of the beam position.

Seventh Embodiment

FIG. 14 shows another example of the magnetic field collectionmechanism. In this embodiment, two superconductive coils are provided asthe magnetic field collection mechanism. In this example, in eachmagnetic field collection mechanism, a superconductive core 32 which isformed of a magnetic body is wound around by a superconductive coil 31and a magnetic field is introduced to a magnetic field sensor 34 by wayof a superconductive circuit 33 so that the magnetic field is detected.Due to such a constitution, it is possible to detect the magnetic fieldwithout always arranging the magnetic field sensor in the vicinity of abeam current. This embodiment is substantially equal to theabove-mentioned embodiments with respect to other constitutions.

Here, a core which constitutes a superconductive core is not alwaysnecessary and it is sufficient so long as a plurality of superconductivecoils is provided.

As described above, according to the embodiments of the presentinvention, it is possible to simultaneously measure the beam positionand the beam current value.

Next, a comparison example is explained.

FIG. 15 shows the constitutions of a mechanism which collects a magneticfield and a SQUID which are used in a beam current measuring device ofthe comparison example. As the mechanism which collects the magneticfield, a cylindrical structural body which has a surface thereof coatedwith a high-temperature super conductive body and has a bridge portionwhich has only a portion thereof formed of a high-temperaturesuperconductive body on the outer peripheral portion thereof is used.Here, the mechanism which collects the magnetic field has one bridge andone SQUID. The constitution of the comparison example includes only onebridge and hence, a surface shielding current flows to the bridge whichis formed of a superconductive body and has zero resistance in aconcentrated manner. That is, the surface shielding current induced onthe surface of the cylindrical body is concentrated on one bridge. Inthis manner, a magnetic field which a beam current to be measuredgenerates is collected, and the magnetic field which the concentratedsurface shielding current generates at the bridge portion is detected bythe detection coil and is measured by the SQUID. Here, even when theposition of the beam which passes a closed curved surface which an innerdiameter of the cylinder forms is changed, a sum of the surfaceshielding currents induced on the inner wall surface of the cylinder bythe magnetic field which is generated the beam is not changed and hence,the beam current can be measured irrelevant to the beam position.Accordingly, as described in the conventional example, the beam currentof several μA can be measured in a non-destructive manner using thehigh-temperature superconductive body. However, it is impossible tomeasure the beam position in the comparison example.

INDUSTRIAL APPLICABILITY

As has been explained heretofore, according to the present invention,the beam current value can be measured with high accuracy in anon-destructive manner and, at the same time, the beam position can bemeasured and hence, the position and the beam current value can beadjusted with high accuracy whereby the beam measuring device isreliably used in fine machining steps.

1. A beam measuring device comprising: a magnetic shielding part,shielding an outer magnetic field; and a plurality of magnetic fieldsensors, arranged in a shielding space which is formed by the magneticshielding part, the magnetic field sensors measuring a magnetic fieldwhich a beam current to be measured generates; wherein the magneticfield sensor includes a plurality of magnetic field collectionmechanisms which collect magnetic fields which the beam current to bemeasured generates; wherein the magnetic field collection mechanisms arearranged such that a superconductive surface shielding current isconcentrated on a predetermined region by interrupting thesuperconductive surface shielding current except for a predeterminedregion on a superconductive surface of the magnetic field collectionmechanisms; wherein the magnetic field collection mechanism is apipe-shaped structural body which has at least a surface thereof formedof a superconductive body and includes a bridge portion which has only aportion thereof constituted of a high-temperature superconductive bodyon an outer peripheral portion; and wherein the magnetic fieldcollection mechanism concentrates a superconductive surface shieldingcurrent which the beam current generates in the vicinity of a pluralityof magnetic field sensors.
 2. The beam measuring device according toclaim 1, wherein an insulator is arranged at the outer wall of thecylindrical structural body in a state that the respective bridgeportion is partitioned so that output of each of the magnetic fieldsensors can easily reflect location of the beam positions.
 3. The beammeasuring device according to claim 1, wherein a normal conductor isarranged at the outer wall of the cylindrical structural body in a statethat the respective bridge portion is partitioned so that output of eachof the magnetic field sensors can easily reflect location of the beampositions.
 4. The beam measuring device according to claim 1, whereinoutput signals of the plurality of magnetic field sensors are connectedto an arithmetic operation circuit which calculates and outputs acurrent value and a position of the beam current.
 5. The beam measuringdevice according to claim 1, wherein output signals of the plurality ofmagnetic field sensors are connected to an arithmetic operation circuitwhich calculates and outputs a current value and a position of the beamcurrent while canceling noise signals having a same phase as the outputsignals of the plurality of magnetic field sensors.
 6. The beammeasuring device according to claim 1, wherein the magnetic field sensoris a SQUID.
 7. The beam measuring device according to claim 1, whereinthe magnetic shielding part, the magnetic field sensor and the magneticfiled collection mechanism include parts which are formed of ahigh-temperature superconductive body.
 8. A beam measuring method whichuses the beam measuring device described in claim 1, arranges the beammeasuring device on the beam line which is radiated to a material to betreated from an ion source or an electron beam source, and measures thebeam current value of the beam line and the position of beams based onoutputs of the magnetic field sensors.
 9. A beam control methodcomprising; a measurement step which measures a beam current of beamswhich are generated by an ion source or an electron beam source usingthe beam measuring method described in claim 8; and a control step whichfeedbacks the beam current value and positions of beams which areobtained by the measuring step or both of the beam current value and thepositions of beams to control parameters of the ion source, the electronbeam source, an analysis electric magnet, a part for applying anelectric field and a magnetic field to beams.
 10. The beam controlmethod according to claim 9, wherein the beam radiation method includesa radiation step which radiates the beam current which is controlledusing the control parameters obtained in the control step of the beam inclaim 12 to a material to be treated.
 11. The beam measuring methodaccording to claim 8, wherein the beam current value of the beam lineand the beam position are simultaneously measured.
 12. A beam radiationdevice which includes the beam measuring device described in claim 1.13. A material to be treated which is manufactured or inspected casingan ion injection device, an electronic beam exposure device, anaccelerator or an electron beam vapor deposition device which includesthe beam measuring device described in claim 1.